The present invention is directed to compositions exhibiting herbicidal activity. Many compositions also exhibit insecticidal and/or fungicidal activity and thus this is also a consideration of the present invention. Preferred embodiments of the present invention combine monoterpene alcohols with fatty acid soaps.
Farming is one manifestation of civilisation and thus for some time man has attempted to clear areas of land for horticulture and agriculture as well as control what type of plants establish themselves there. In earlier times the methods used focused on physical effort or fire to remove and control weeds or unwanted growth. As time progressed it was recognised that various types of chemicals had an adverse effect on many plants and were an efficient alterative to labour intensive methods of control. With the rapid advance of the chemical and petro-chemical industries in the 19th and 20th centuries, chemical sprays for the control of not only plants but also fungus and insects etc. proliferated. Currently there is a wide range of insecticides and herbicides available which are based solely or predominantly on synthetic chemicals.
However, of more recent times there has been increased consumer backlash against the use of synthetic products, or products which are perceived not to be of natural origin. This consumer resistance is at least partially based on problems and difficulties associated with the use of chemicals in agriculture. The use of insecticides is one graphic example where for some time the problems of residue run-off entering the eco-system has caused problems down the food chain. As a consequence, much research has gone into the development of new synthetic insecticides which address this problemxe2x80x94typically by the use of products which bio-degrade quickly in the environment and/or are less likely to interfere or harm animals further up the food chain. Another solution has been to place more dependence upon the use of naturally occurring insecticides, many of which have been found to occur naturally in plants.
Herbicides represent a different area and have different problems. Here there are still problems with run-off and residues. Toxicity to animals and humans is also a major problem. For instance, the use of herbicides of the paraquat family have been tightly controlled or banned in many countries.
Residues represent a problem insofar as it is often desirable to sow over cleared ground as soon as possible after defoliation. Many herbicides have a residual period before re-sowing or over-sowing can occur. A further problem relates to residual compounds in the dead foliage. These may remain in the foliage until bio-degraded or otherwise eliminated into the environment. Having to physically remove dead foliage to allow immediate resowing is not a viable option in most instances.
The art has sought to address many of these problems. The glyphosate family of herbicide are very important commercially and are widely used where compounds of low toxicity and short residual life time in the soil are required. However, these compounds still represent synthetic products which are still resisted by the public""s swing to naturally based products and organic farming.
While many insecticidal compounds occur naturally and have been identified (e.g. the pyrethrins) there is no such plant based herbicidal compounds in the art. This perhaps appears not to be surprising, for while many plants have evolved to produce compounds which repel or kill insects which may affect them, it is relatively uncommon, if at all observed, for plants to have to control other plants in a herbicidal manner. Accordingly, one cannot merely look directly to nature to provide an immediate solution to the aforementioned herbicidal problems.
The present invention seeks to address at least some of the problems associated with such prior art. In particular it seeks to provide compositions (and their use) for horticulture and agriculture which are based primarily on naturally occurring or derived substances and which are active in their preferred area of application without the need of compounds and substances which are generally regarded as being synthetic or non-organic. However, this is not to say that synthetically produced analogues of naturally occurring substances are not within the scope of the present invention, or that simple synthetic derivatives of the naturally occurring compounds are excluded either. It is also envisaged that chemical and industrial techniques may be used to extract or render the natural materials into a usable form.
It is recognised that a distinction in agriculture between organic and no-organic compounds is, in many instances, purely semantic. In many instances there is no chemical or biological difference between a naturally sourced or naturally occurring substance, and that substance when produced synthetically. In some instances the synthetic analogue may be cleaner, purer, and more cost effective. So, for the purposes of this specification, naturally occurring shall mean substances which occur naturally in nature, rather than the manner by which they were obtained or prepared.
Further, when reference is made to derivatives of these compounds, this shall generally mean derivatives which do not substantially differ in chemical structure or properties from the naturally occurring compound. By way of example this would generally mean one or two relatively simple substituted groups on the original compound, or compounds which have added on to or reacted with functional groups on the original compound. These substituted or added groups could also be of a relatively small size (e.g. up to C5 or a simple functional group) rather than being of a size or character so as to dwarf or obscure the original naturally occurring compound. Some examples, which are meant to be illustrative only rather than limiting, include soluble salts of original compounds, and the substitution or addition of simple alkyl groups etc. The main exception to this description would be esters, in which case it is desirable that the added ester group is relatively small, or comprises another naturally occurring product.
Some of the problems outlined above have been recognised in the prior art and at least the specification of WO 97/16975 considers the use of certain plant derived products. In particular, pine oils, pine alcohols, pinene, dipentene and d-limonene are advocated. Their combination with tea tree and/or eucalyptus oils, is claimed to exhibit synergy. However, preferred embodiments of this specification require distillation of natural oils and extracts to leave substantially pure terpenes of interest. This can add substantially to the expense of the composition, which is a significant factor in agriculture.
For use, the active terpenes specified in WO 97/16975 may be diluted with a suitable carrier, and a number of plant oils are listed. However, many of these oils are relatively expensive, and the application of non-volatile oils may in some circumstances be undesirable, depending upon the quantities distributed. However, in preferred embodiments of WO 97/16975 the substantially pure, distilled, compounds are applied undiluted to foliage.
The present applicant has found that direct application of the terpenes in the manner specified within WO 97/16975 may suffer from some disadvantage. For instance, the volatility of many of the components may cause them to flash-off from foliage before they are able to exhibit a herbicidal effect. This is particularly true in hot weather, and when foliage is exposed to direct sunlight. Accordingly the present invention also seeks to address this problem other than by merely increasing the quantity of active compound applied. By way of example the present invention also considers enhancing the effectiveness of active components.
The present invention also seeks to address the necessity for using highly purified, or distilled components such as advocated in WO 97/16975, or seeks at least to suggest alternatives thereto. Other aspects of the present invention nay also address other perceived shortcomings with prior art such as disclosed in WO 97/16975, such as rapidity of action.
It is therefore an object of the present invention to consider and attempt to address the foregoing problems and perceived limitations of the prior art, or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.
According to one aspect of the present invention there is provided an agricultural composition including a combination of:
a) at least one monoterpene alcohol as defined herein, and
b) a fatty acid soap and optionally including one or more carriers or diluents.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above in which the oil is a pine oil.
According to another aspect of the present invention there is provided an agricultural composition as claimed in any one of the preceding claims in which the fatty acid soap is derived from the reaction of a tall oil with an alkali.
According to another aspect of the present invention there is provided an agricultural composition as claimed in any one of the preceding claims in which, excluding optional carriers and diluents, there is present at least 30% by weight of monoterpene alcohols as defined herein.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above, in which there is present, excluding optional carriers and diluents, at least 55% by weight of pine oil.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above in which there is a minimum total alcohol of 60% by weight in the pine oil.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above, in which in addition to the pine oil there is included either or both of additional monoterpene alcohols, or plant derived oils containing same.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above in which, excluding optional carriers or diluents, a maximum of 35% by weight of tall oil and fatty acid soaps derived therefrom are present.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above in which, excluding optional carriers or diluents, between 12 and 25% inclusive by weight of tall oil and fatty acid soaps derived therefrom are present.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above in which, apart from optional carriers or diluents, at least 25% by weight of fatty acid soap is present.
According to another aspect of the present invention there is provided a herbicidal composition substantially as claimed above which includes one or more of water, and water-miscible solvents.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above which includes one or more of the following optional components: surfactants, foaming agents, emulsifiers, pesticides, compatible fungicidal agents, fertilising components.
According to another aspect of the present invention there is provided an agricultural composition substantially as claimed above which includes one or more of the following optional components: colourants, dyes, pigments.
According to another aspect of the present invention there is provided a composition, substantially as described above, which includes one or more of the following:
a terpineol, borneol, isoborneol, an anethol, a fenchol, a chavicol, a terpinene, limonene, citronellol, a pinene, camphene, camphor, a fenchone, a thujone, thymol, eucalyptol, dipentene, eugenol phellandrene, ascaridole, cedrene, carvone, or anethole.
According to another aspect of the present invention there is provided a composition, substantially as described above, also exhibiting insect repellent abilities.
According to one aspect of the present invention there is provided a composition substantially as described above, diluted with water to a concentration below a thresh-hold in which there is significant herbicidal action, for use as a pesticide or fungicide.
According to another aspect of the present invention there is provided a composition, substantially as described above, characterised such that when the composition is sprayed onto foliage a foam comprising a plurality of bubbles is created.
According to another aspect of the present invention there is provided a composition, substantially as described above, in which the foam comprises at least a monolayer of bubbles across the surface of the foliage.
According to another aspect of the present invention there is provided a composition, substantially as described above, in which the longevity of the foam is sufficient, under shaded, substantially wind and rain free conditions, is of a time during which the composition has caused visible and/or irreparable harm or damage to the plant.
According to a further aspect of the present invention there is provided a method of preparation of an agricultural composition in which fatty acid soap is prepared from the reaction of fatty acid with an alkali material, and in which there is introduced into the composition at least monoterpene alcohol.
According to a further aspect of the present invention there is provided a method substantially as described above comprising the steps of:
i) combining the fatty acid and monoterpene alcohol portions;
ii) dissolving an alkaline material in water;
iii) reacting the components of steps i) and ii).
According to a further aspect of the present invention there is provided a method substantially as described above in which the monoterpene alcohol is introduced as pine oil.
According to a further aspect of the present invention there is provided a method substantially as described above in which the fatty acid is introduced as a tall oil from pine.
According to a further aspect of the present invention there is provided a method substantially as described above comprising the steps of:
i) combining a pine tall oil with a pine oil having a total alcohol content of at least 60%, the proportion of tall oil to pine oil being within the range of 10:80 through 25:60 inclusive;
ii) dissolving a metal hydroxide in water;
iii) combining the dissolved hydroxide with the components of step (i) and allowing to react until a soap is formed;
iv) optionally including any additional components.
According to a further aspect of the present invention there is provided the use of a composition substantially as described above as a selective foliar applied herbicide, said use comprising dilution of the composition to within a range defined by observable thresholds with an upper limit being the concentration for significant or irreparable damage to desirable plants, and a lower limit being no significant damage to targeted plants.
According to a further aspect of the present invention there is provided the use substantially as described above in which the upper limit is defined by 10% or more of desirable plants being killed, and the lower limit by less than 10% or more of targeted plants being killed.
According to a further aspect of the present invention there is provided the use of a composition substantially as described above in as a pesticide or fungicide, comprising diluting the composition to below a level in which significant or irreparable damage is inflicted on desirable plants.
According to a further aspect of the present invention there is provided the use of a composition substantially as described above, as a combined herbicide and either or both pesticide or fungicide, in which the composition is applied at a concentration sufficient to inflict significant or irreparable damage to targeted plants.
According to a further aspect of the present invention there is provided the application of a composition, substantially as described above, in a manner inducing to form a foam substantially coating a surface to which it is applied with a monolayer of bubbles, whose duration is such that after 5 minutes of shaded, wind free conditions at 20xc2x0 C. on a non-porous plant foliage surface at least 50% of the original foam covered surface still remains covered.
According to a further aspect of the present invention there is provided the use substantially as described above for pesticidal applications, in which the method of application maximises the production of foam or entrapped bubbles in the applied mixture.
According to a further aspect of the present invention there is provided the use of a composition substantially as described above, for pesticidal or herbicidal applications, in which the composition is applied in a manner in which at least a monolayer of bubbles are formed over at least 50% of the leaf foliage surface area to which the composition is applied.
According to a further aspect of the present invention there is provided the use substantially as described above in which application is by spray in an air stream.
According to a further aspect of the present invention there is provided the application of a composition, substantially as described above, a method for killing or severely damaging plants comprising the application of a phytoactive compound comprising at least one of a mono-cyclic monoterpene alcohol, bridged mono-cyclic monoterpene alcohol, or alcohol derivative of the foregoing, in combination with a fatty acid soap and under conditions in which the phytoactive compound is introduced to significant foliar surface area of the plant under conditions in which the phytoactive compound remains in contact with the plant""s foliar and/or sub-foliar regions, for a period of time sufficient to cause cell damage and/or interfere with plant function in those regions.
According to another aspect of the present invention there is provided a method, substantially as described above, in which the phytoactive components are protected from early evaporation and kept in contact with the plant through the use of a blanketing cover of foam.
A primary role of the present invention is to control and/or eradicate plant life. Many herbicidal, compositions according to the present invention may not be phytotoxic to all plants, and/or may only be phytotoxic after repeat applications or when applied in sufficient quantity. However for the purposes of simplicity, we shall use the term xe2x80x98herbicidalxe2x80x99 to include both the eradication as well as control of at least some, if not all, known plants.
Secondary roles of the present invention include pest and insect related applications, as well as fungal related applications. By this is meant the use in the role of an insecticide as well as uses in repelling or limiting the effect of pests and insects on applied areas. This relates to the control of pests either by limiting their number through eradication or repulsion, or making the targeted areas unattractive to the pests. The term xe2x80x98pestsxe2x80x99 with the specification will generally refer to insects as well as arachnids.
A similar definition applies to fungicidal aspects of the present invention.
The present invention makes use of a number of compounds which occur naturally in a number of plants. More specifically these comprise a number of monoterpenes, which will be described more fully later within this specification, and preferably monoterpene alcohols. The use of a number of these compounds have been documented in the prior artxe2x80x94for instance in WO 97/16975. However, as discussed previously, there are some disadvantages associated with the use of these compounds alone.
The present invention has sought to address this through the combination of such monoterpene compounds with fatty acid soaps. While it is not fully understood whether these soaps, or the vehicle in which they are presented (tall oils in preferred embodiments) there appears to be a useful advantage obtained through their inclusion. Whether observed enhanced effects over the use of straight monoterpenes is due to toxicity of the soaps, or their role in prolonging contact of monoterpene actives with the plant (this role will be described more fully later herein), or as a result of both, is not known. However, there appears to be advantage obtained through the use of particular monoterpenes (and in particular the alcohols) in combination with fatty acid soaps (and particularly those derived from tall oils).
There are a number of potentially realisable advantages associated with the various embodiments of the present invention. Among the advantages which may be exhibited in the various embodiments include very rapid action on many plants, minimal residual phytotoxic effects, low toxicity to animals, and the fact that they are primarily based on naturally occurring compounds. This represents significant and useful advantages as well as offering the public further choice in the selection of horticultural and agricultural compositions.
As indicated above, the exact mechanism of how the present invention works is not fully understood. However it is considered that plant detrimental phytoactive effects caused through the use of the present invention include dehydration and irreversible plant cell damage. This is at least partially based on observations and trials of the present invention where observable damage occurs in leafy plants in and periods of less than one hour. This is in contrast to many of the hormonal types of substances which may take several weeks to have a marked effect. It has therefore been concluded that such rapid observable manifestations of activity result from physical damage to the cell structure of the plants in at least the foliar and sub-foliar areas.
As the invention appears to cause plant damage in the leafy areas, this in turn has varying degrees of effect on plant functions associated with these areas. This includes interference with photosynthesis, transpiration and respiration. Hence, while more delicate plants appear to succumb rapidly and irreversibly from the first observable effects of dehydration and/or cell damage, the more difficult plants continue a decline due to a severe reduction in their ability to function properly. Typically the damage caused by application of the invention (over one or more applications) damages parts of the plant past the point from which the plant can recover.
In the prior art the invention of WO 97/16975 relies on the use of related compounds to the actives specified herein. However there appears to be a significant difference in the rapidity of action between the present invention (substantially faster) and the data outlined in the prior art specification. While it is difficult to draw a direct comparison between two such groups of differently trialed data, it would appear to support that the added fatty acid soap either (or both) enhances the effect of the primary active components, or acts as an active component disrupting plant function.
The rapidity of activity also supports that embodiments of the invention do not act as a phytotoxin, but rather damages the plant so it can no longer function and survive. This appears to be further supported by the negligible residual activity allowing rapid resowing and replanting of sprayed areas of land.
Preferred primary phytoactive compounds for use in the present invention comprise monoterpene alcohols, including in particular the alcohols of mono-cyclic monoterpenes, internally bridged mono-cyclic monoterpenes, and mono-cyclic monoterpenes (including both bridged and unbridged) whose mono-cyclic ring is unsaturated, as well as derivatives of the foregoing.
For simplicity of description, the term xe2x80x98mono-cyclic monoterpenexe2x80x99 shall when used within this specification, unless otherwise specified, refer to both bridged and unbridged mono-cyclic monoterpenesxe2x80x94the bridge being an internal bridge across the ring, as well as mono-cyclic monoterpenes whose mono-cyclic ring is unsaturated.
Less preferred primary phytoactives for use in the present invention include the aldehydes and ketones of mono-cyclic monoterpenes (as defined above). However the preference is for the use of monoterpene alcohols and when the aldehydes or ketones are used the preference is for the use as a secondary active component in addition to monoterpene alcohols as the primary active component.
Also of interest as phytoactive compounds in the present invention are derivatives of the foregoingxe2x80x94a discussion of what is regarded as being derivatives within the scope of the present invention has previously been given.
There are a number of compounds which fall within the above group of phytoactive compounds. As can be readily ascertained, these are based on monoterpene compounds which comprise a broad group of compounds derived from the bio-synthesis of (typically two) C5 (typically isopentene) units. The resulting monoterpene compounds are typically C10 compounds and may be linear, bridged, or cyclic.
Examples of some preferred phytoactive compounds falling within the above grouping include the borneol family of compounds (representative of bridged cyclic monoterpenes), the terpinene families (including the various terpinenes which are representative of monocyclic monoterpenes in which there is a degree of unsaturation in the monocyclic ring), terpineols (which are representative of monocyclic monoterpene alcohols). There are also a number of other phytoactive compounds falling within the above definitions. These include, but are not restricted to, compounds in families including: the terpineols, the borneols, the isoborneols, the anethols, the fenchols, the limonene family, the pinene family, the camphene family, the thujol family, dipentene, the eugenol family of compounds, the phellandrene family, and the carvacrols. In the context of the group of (primary and secondary) phytoactive compounds, the above groups and families should generally be taken to mean the alcohols, ketones, and aldehydes but may also include cyclic compounds bridged by an oxygen atom.
In practice, embodiments of the present invention may comprise only one of the group of phytoactive substances. However, as it is envisaged that most of these will be derived from natural sources, it is envisaged that there will commonly be present more than one of these phytoactive components. This may be economically sensible as well, as purification of naturally derived products to exclude other components present is often both unnecessary and not cost effective. In additionxe2x80x94and it should be appreciated that the mechanisms of the invention are not fully understoodxe2x80x94it is considered that while the actions of the various phytoactive compounds are equivalent in action they are not necessarily identical. There may be some variation in the activity of different members of this group, and this will also depend upon a number of other factors including the species of plant to which it is applied, the conditions under which it is applied etc. Where a non-selective herbicide is desirable, there may be some advantage in including two or more of the phytoactive components in a composition.
Similarly, there may be some advantage in including a number of other naturally occurring components in compositions according to the present invention. Envisaged are non-monoterpene compounds which are nevertheless very related to the monoterpenes and often occur naturally in some plants in conjunction with members of the phytoactive group. Examples of some of these additional components include the chavicol family, the citronellol family, and ascaridole family of compounds.
In a preferred embodiment of the present invention, the oil of an evergreen tree, rich in preferred phyto-active components, forms the basis for introducing the active compounds into the composition. Preferred evergreen trees are conifers, and for commercial reasons pine is preferred. The preference is to use oils which are rich in monoterpene alcohols (as defined herein) and preferably having a total alcohol content of at least 50%, more preferably 60%, and ideally at least 80% by weight.
By xe2x80x98total alcohol contentxe2x80x99 is meant the percentage, by weight, of the material being considered which comprises compounds which are alcohols.
Preferred oils for introducing monoterpene compounds, according to the present invention, are pine oils. Pine oils vary in composition according to a number of factors. Preferred pine oils for use with the present invention are those having a total alcohol content of at least 60%, and more preferably at least 80%. It is also preferable that the majority of these alcohols comprise terpineol or pinene. A typical assay of a suitable pine oil is given in the examples.
The total alcohol content of the pine oil, or other components used for introducing monoterpene alcohols, will have a bearing on the required percentage of the oil (or component) in a concentrate formulation. Typically for a concentrate, to be diluted such as outlined in the ensuing examples, a minimum monoterpene alcohol content of at least 25% is desirable. More preferably 40%, and ideally at least 50% in the finished concentrate. This is assuming a concentrate possessing a maximum of 10% of diluents and carriers. Calculations may be performed to find equivalent desirable levels for compositions with other carrier/diluent levels.
The use of secondary active compounds have already been noted. It is envisaged that such secondary actives may be used to supplement monoterpene alcohol levels, though it is preferred that at least the minimum levels of monoterpene alcohols outlined above are present. However, a composition having only a 25% level of monoterpene alcohol will be more effective if there is, for instance, another 25% of monotone aldehyde or ketone also present as a secondary component as opposed to carriers, diluents, or non-active components.
It is also noted that commercially available xe2x80x98naturalxe2x80x99 pine oils are often rich in sulphur compounds as a consequence of the methods by which they are extracted. The raw products may be further refined to remove these sulphur compounds. Either form may be used in embodiments of the present invention. The choice will often be a compromise between cost, and the acceptability of one form over the other in the market place.
Present in embodiments of the present invention are enhancing agents able to enhance the activity of the preferred active components. In the preferred embodiments of the applicant, these enhancers comprise fatty acid soaps. These components appear to enhance the activity of the primary active components (i.e. the monoterpene compounds) as well as enhancing the rapidity of their action. Yet further, this also appear to extend the usefulness of compositions according to the present invention for pesticidal and anti-fungal roles.
Fatty acid soaps used generally comprise the salt of a fatty acid with a suitable cationxe2x80x94usually sodium or potassium. For economy, most fatty acid soaps in the present invention will have sodium as the cation, while the fatty acid will often be predominantly based on an alkyl in the C14-C22 range.
The source of the fatty acid may vary. This may comprise compositions materials rich in fatty acids and which have been derived from natural materials. The preference is to use plant derived materials. Preferred embodiments of the present invention, and particularly those using pine oil, utilise tall oil as the fatty acid source. This is typically reacted with a suitably alkaline agent, typically sodium hydroxide, to produce a soap.
As mentioned previously it is considered that the full nature of the role of the fatty acid is not understood. It is anticipated that part of the effectiveness of the present invention may result at least partially from the ability of the fatty acid soap to encourage a layer of bubbles or foam which inhibit evaporation of the primary active components (the monoterpene compounds) from foliage. It is also considered that the fatty acid soaps may also be active in disrupting plant function, disrupting cellular or macro cellular processes in structures etc. The part hydrophilic and lipophilic nature of the soaps may also assist in enhancing the effectiveness of the primary active components, as well as interfering with the processes and structure of the plant.
It is also anticipated that other components in reagents such as tall oil may also be active in disrupting plant function. This may be one reason why the pine oil and tall oil based preferred embodiments of the present invention are especially effective.
The role of the carrier and diluents which are optionally used in conjunction with the present invention (they may not be present, or present only in limited amounts, in concentrates but are generally included in ready to use compositions) needs to be considered. The use of a suitable carrier or diluent, and in particular water, may extend beyond the mere use as a diluting agent for distribution of the other components. This will be described further below.
Hence, while it is envisaged that the above compounds will have an adverse effect upon plant material to which it is applied, application of the concentrated substances is generally economically impractical and expensive. For this reason it is generally desirable to include a suitable carrier for when the compositions are to be applied. While this could conceivably include suitable organic solvents, the difficulty in working with these carriers in an agricultural environment will generally preclude their use. Such difficulties include flammability and explosion dangers, as well as regulations governing the release of solvents into the environment. For this reason, preferred embodiments of the present invention will rely on water as the preferred carrier.
Another composition involves the conditions upon which the spray is generally applied. In many environment volatile organic substances will flash off relatively quickly. If this happens too quickly, then the applied phytoactive components may be incapable of establishing the intimate contact with plant material required to result in plant damage. For this reason it is desirable to have a spraying composition which will promote or encourage intimate contact between the phytoactive components and the plants to which the composition is applied.
The use of water as a carrier goes some way towards solving this problem as water is not particularly volatile in comparison with many organic solvents and compound. In addition the bulk of the water may have a slight cooling effect on the foliage so that any applied organic compounds are less likely to evaporate off. Further, water (though this is also true of some organic solvents) will readily migrate into the plant surface and may help carry with it any dispersed phytoactive components, particularly in combination with the presence of soaps, and optionally included additional components such as surfactants.
While such additional components may include surfactants and wetting agents, many wetting agents and surfactants are of synthetic origin and may not be permissible for organic farming methods. Consequently their use may preclude the present invention from being used in an area for which it was at least ally developed. Secondly, many surfactants and wetting agents alone (in lieu of the fatty acid soaps) will not necessarily provide another advantage of preferred embodiments of the present invention. This further advantage comprises the ability, under ideal spraying conditions, to a least partially insulate the phytoactive components from the environment while they have a chance to work on the plant surface to which they are applied. Quite simply this can be achieved by the provision of a protective layer against rapid loss or evaporation of the phytoactive components and to also direct their action towards the plant. In practice this is found to be accomplished by the use of compositions which produce foam when sprayed onto the plant surface. In the present invention, the fatty acid soaps afford the foaming properties, though these may be enhanced by other commercially used and known foaming agents, or substances which increase the stability of foams or bubbles.
The insulating foam produced upon application need not be a substantial foam, but may merely comprise a monolayer of bubbles over the surface to which the composition is applied. This need not be the entire surface though ideally should cover at least 50% of the surface area, and more preferably at least 60%.
The probility of the foam or bubble structure is another consideration. Ideally, such a foam would be long lived though in practice may have a half-life of the order of 3-5 minutes. In some instances shorter lived foams are also acceptable though a general preference would typically be foams whose duration is as follows:
preferably, under shaded wind-free conditions at 20xc2x0 C., applied to a broad-leafed plant surface which is not especially porous, at least 50% of the original surface area covered by foam or bubbles will still remain after 2 minutes;
more preferably, under the above conditions, the same proportion of surface area should still remain covered by foam or bubbles after 5 minutes, and
even more preferably, the same proportion of surface will be covered after to 10 minutes.
A particular test which may be applied is given in the detailed examples hereafter.
It should be envisaged however that different conditions will have an influence upon what is acceptable in practice. Under higher ambient temperatures, the action of the phytoactive components may be quicker and absorption into the plant may also be quicker. Under these conditions foams which last a lesser period of time may be acceptable.
Similarly it is envisaged that as the applied composition migrates into the plant structure, the ability to maintain a foam on the surface will also be lessened. In many instances, destruction of the foam or bubble structure is a result of the applied composition having the desired effects and entering into the plant. Under such conditions, it would no longer be necessary to maintain a protective foam layer as the components will have already performed a substantial proportion of their job. It is envisaged that many broad-leafed plants will fall into this category while other plants, and especially those having waxy surfaces slowing penetration of the phytoactive components, may require the foam/bubble covering to protect it from the environment for greater periods of time. These considerations should be borne in mind when preparing compositions of the present invention, and also in the preparation of their final spray compositions. However it is noted that tall oils are particularly effective in dissolving waxy substances and thus embodiments including tall oil fractions will exhibit increased effectiveness against plants having waxy leaves or foliar surfaces.
It is envisaged that there may be different embodiments destined for different types of application e.g. broad-leafed v. woody or difficult plants. Here the portion of components may vary to address any particular problems associated with that type of plant or grouping.
While foams may be produced by a number of different effects, it has been found in trials by the applicant that a useful foam structure may be achieved through the inclusion of fatty acid soaps with the phytoactive components. Common sources of fatty acids including those derived from plants (e.g. some tallol""or tall oil formulations) represent a useful source of fatty acids for use in the present invention. These are usually reacted with a suitable alkaline material to form a soap for use in compositions of the present invention.
The use of fatty acids and their soaps appears to give a foam structure, particularly when combined with water as a diluent and applied with an air carrier, contributing to many of the advantages discussed before. However, it also appears that the use of these fatty acids and their soaps, as well as satisfying criteria for the use of organic compounds (insofar as the term organic is used in relation to agriculture), enhance the activity of the phytoactive components. As has been mentioned previously, the exact mechanisms of the present invention are not fully understood though initial trials indicate that the combination of the phytoactive components with fatty acids and their soaps yields a highly effective herbicide with a very rapid effect (see also examples later herein).
Accordingly, preferred embodiments of the present invention comprise a combination of the preferred phytoactive components with substances able to produce a covering foam, but most preferably where the substances include or are based on fatty acids. At this stage there is no indication that any particular fatty acid is preferable to others though there may be some benefit in using fatty acids derived from plants, which represent one major commercial source of fatty acids, and particularly using tall oil.
Various compositions may also include a number of additional optional components. These may include active compounds which perform a particular role. These may merely rely on the compositions of the present invention as a carrier for their distribution, or may actively participate in how the present invention works. In the former category, these may include additional insecticides, fungicides, or other agricultural chemicals which act separately from the present invention. It is anticipated that their inclusion is primarily to avoid the user making two spray applications to plant material, though it is also envisaged that there may be some additional advantages which result from the combined use.
In the second class are components which participate in the working of the invention, or its usefulness. This may include surfactants and wetting agents as mentioned above. In addition this may include additional foam enhancing agents. These may be agents which produce a foaming effect, or may alternatively prolong the life of any bubbles or foam produced in the present invention. A number of such agents are known commercially in these roles and may be employed in the present invention, providing the composition still conforms with user requirements (e.g. the presence or absence of non-organic materials).
Other components which may be optionally added include pigments and colourants. This may simply for the role of enhancing the aesthetic appeal of the product (or for practical reasons such as to distinguish it from other substances. In addition it may serve a role as a marking for areas of foliage which have been sprayed, which would be particularly useful for aerial application of the present invention. Other optional components commonly used within the agricultural industry may also be considered for inclusion in the present invention.
Also included within the scope of the present invention are uses of the compositions. In most cases the main role of these compositions will be as a herbicide. This will typically be as a non-selective herbicide, and providing a suitable concentration is used, a useful non-selective herbicidal action against most plants can be achieved.
Methods of use may include repeat applications. This will tend to emphasise the effects of earlier sprays and may be used to address plant growth which missed the first spraying pass, or which survived that pass.
The present invention may also be used in a selective manner. Trials suggest that the present invention is most effective against broad leaf plants. Accordingly, there is application for the present invention as a selective broad leaf herbicide. Such uses will rely, as for most selective herbicides, upon the greater effect of the herbicide on some plants than others.
Compositions used for selective applications will usually be diluted to within a particular range of dilutions. While this will depend also upon the application rate, a typical dilution will be selected to fall within a range of threshold values falling below the point where desirable plants are affected adversely, but above the point where there is minimal harm to targeted plants. While user acceptability may differ, it is typically envisaged that the compositions will be applied in a manner such that no more than 10% of desirable plants are irreparably or significantly damaged and impaired. Similarly, there should be at least 10% mortality rate in targeted plants. In some instances either or both of these limits may be increased or decreased, depending upon acceptability. However, it should also be considered that a lower degree of mortality may be acceptable for when the composition is being used in manner to slow the growth of targeted plants so as to provide desirable plants with a competitive advantage.
Typical selective herbicidal uses of the present invention may include lawns, weed control between trees and saplings (e.g. in forestry, orchard, and plantation) as well as weed control between crops. In some of these applications a greater degree of selectivity may be achieved by limiting application of the herbicidal composition to the vicinity of the targeted plants. This will minimise the impact of the composition on desirable plants, as well as reducing wastage of composition. Because the effectiveness of the present invention appears to be greatest when applied to foliage, it may find use for controlling weeds in between crops, as well as in forestry and plantations where compositions sprayed onto the basal area of trunks and stems of desirable plants may have a minimal effect compared with the control of the targeted weeds.
It has also been noted that the present invention can also exhibit pesticidal and fungicidal activity. Again in these applications a dilution and rate of application is generally chosen to avoid damage to desirable plants but to provide a useful level of pest and fungal control. In particular it has been noted that the foaming nature of the present invention is particularly effective against sucking and chewing pests. As for plant foliage, the layer of bubbles/foam appears to trap the active components over the body of the pest until such time as it has exhibited a toxic effect. In addition, there may be suffocation of the pest which literally drowns in the foam.
Finally, it is envisaged that the present invention may be used in a combined role where it may act as a herbicide as well as either or both a fungicide or pesticide. In such instances, lesser dilutions may be used. Particular uses may include spraying between other desirable plants to control weeds. The anti-fungal properties can delay decomposition such that the affected plant material tends to dry first. Such material tends to more slowly break down and in the interim period tends to act as an effective mulch. This application may be particularly useful in drier areas.
The following examples are given by way of example only. They are not meant to be limiting but merely demonstrative of some various ways by which the present invention may be implemented, prepared or formulated.